1. Field of the Invention
The present invention relates to the use of a secret quantity coming from an integrated circuit or from an electronic sub-assembly element containing such a circuit. For example, the present invention relates to the use of such a secret quantity by programs, as an encryption key, as a secret quantity of an integrated circuit identification or authentication process. The present invention more specifically relates to integrated circuits capable of executing several different application programs, be these programs contained in the integrated circuit or the electronic sub-assembly containing it or housed in distant systems.
2. Discussion of the Related Art
An example of application of the present invention relates to smart cards where the integrated circuit chip can be used for several purposes (for example, electronic payment, identification of the holder, etc.). In this case, it is desirable not to use the same secret quantity (digital datum) (of integrated circuit authentication or data encryption) for all the application programs likely to use this chip. Indeed, if a pirate attempts to executes a fraudulent application program from the integrated circuit chip, the secret quantity of the chip is also used. The distant system executing the fraudulent application can recover the secret quantity or key of the chip. This quantity can then be fraudulently used for other applications.
To avoid this type of fraud, conventional systems using smart cards in which the transmission with the exploitation terminal can be performed with or without contact, provide that the secret quantity of the chip is not read by the application program but is generated on request of the application program by the smart card operating system (for example, an operating system known under trade name JAVACard).
These conventional solutions require significant resources in terms of programming to execute the authentication or encryption process.
The present invention more specifically relates to the generation of distinct secret quantities according to the applications.
Among means for generating a secret quantity within an integrated circuit, the solutions using storage elements and those causing a generation of a binary word based on a physical parameter network linked to the integrated circuit manufacturing are essentially distinguished.
It could be thought to multiply the number of physical parameter networks so that they correspond to the number of applications that the integrated circuit can process. However, such a solution requires much more space and comprises a non-negligible risk of obtaining identical secret quantities generated by the physical parameter network.
Further, each application may require a minimum size of the secret quantity greater than the size of the quantity directly provided by the physical parameter network.